Protectors for protecting timber poles against subsoil decay

ABSTRACT

The invention relates to a protector for protecting a timber pole against subsoil decay. The protector, referred to specifically as a field liner, comprises a flexible sheet element in the form of a laminate structure including a plurality of material layers that provide the sheet element with required properties to serve as a field liner. For its field liner application the sheet element is used either in its sheet form as such, or in a sleeve form, both forms providing for the sheet element to be wrapped around a pole to be protected, the sleeve form providing for such wrapping after having been applied over the pole to cover the region to be protected. An adhesive substance applied to a suitable region of the sheet element then permits securing of the sheet element on the pole in its operative configuration tightly wrapped around the pole.

THIS INVENTION relates to protectors for protecting timber poles againstsubsoil decay.

It is known, as a method of primary pre-treatment of a timber pole to besupported in a body of soil, to apply a protector, also known as andherein referred as a field liner, to the pole, for covering the regionof the pole that will be disposed within the soil body. A known fieldliner comprises a sleeve, of a synthetic plastics material, which, inuse, fits snugly around the pole to be treated thereby, along the regionof the pole to be covered, the known method of fitting this field lineron the pole providing for the sleeve to be heat shrunk on the pole.

The synthetic plastics material forming a field liner generally is aliquid impermeable, non-biodegradable material such as polypropylene, ora low density polyethylene. By its application on a pole it covers theoptimal fungal growth region of the pole, thereby regulating atsub-optimal levels the air and moisture content of the said region, andisolating it from nitrogenous compounds that exist in soil, all of whichare required for fungal growth to occur. The field liner thusspecifically prevents fungal growth from occurring. Since it is appliedin the form of a sleeve, of which the operative lower end is open, thetransverse surface of the butt of the pole remains uncovered and by notencapsulating the butt, it cannot become anaerobic and, as such, thefield liner also prevents subsoil decay by anaerobic bacteria.

The heat shrink method of applying a field liner on a pole, althougheffective, has proved to be difficult to carry out in practice,particularly in a cheap and time efficient manner and it is thus anobject of this invention to provide a field liner in respect of whichthe application on a pole is facilitated.

It has also been found that preservatives in standing poles migratedownwards through outer sapwood vessels and are then lost to the soil byleaching from the poles, particularly from longitudinal and transversefaces of the poles near the butt ends thereof and that are in soilcontact. The preservative loss is reduced by known field liners, but itremains an object of this invention to ameliorate the problem ofpreservative loss still further.

According to the invention there is provided a field liner forprotecting a timber pole against subsoil decay, which includes a sheetelement in the form of a laminate structure including a first layer of aflexible, liquid impermeable, non-biodegradable synthetic plastics filmmaterial that contains a dry film biocide therein and a second layer ofa flexible, liquid impermeable, non-biodegradable synthetic plasticsfilm material that is tear resistant, the sheet element being configuredto permit wrapping thereof around a pole for covering the region of thepole to be protected and having an adhesive substance applied thereto ina region thereof that permits securing of the location of the sheetelement on a pole when wrapped around the pole with its first layerabutting the pole by adhering the said region of the sheet element to anopposing region of the sheet element when wrapped around the pole.

A first embodiment of such a field liner provides for the sheet elementto be configured to define a rectangular configuration, that permitswrapping thereof around a pole by winding it on the pole, the adhesivesubstance being applied to the sheet element as an adhesive strip alongan operative longitudinal edge region thereof.

The sheet element of such a field liner may be provided on a rollincluding a plurality of sheet elements, being separable from the rollby severing along a defined line of weakness, e.g. a line ofperforations.

A second embodiment of the field liner of the invention provides for thesheet element to be configured to define an elongate sleeve that has thefirst layer of material forming the operative inside thereof and thesecond layer of material forming the operative outside thereof, thesleeve permitting loose location on a pole for covering the region ofthe pole to be protected and hence wrapping around the pole into a tightconfiguration of the sheet element on the pole, the adhesive substancethus being applied externally on the second layer of material in aregion thereof that permits securing of the location of the sheetelement in its said tight configuration on a pole when wrapped aroundthe pole by adhering the said region to an opposing region of the sheetelement when wrapped around the pole in the said tight configurationthereof.

One end of the sleeve defined by the sheet element of such a field linermay be at least partially sealed to form a pocket, the at leastpartially sealed end of the sleeve, in use, serving to determine thelocation of the sleeve on a pole by preventing the butt end of the poleto extend beyond the said at least partially sealed end of the sleeve.When so partially sealed, the pocket formation will have an openingtherein that, in the operative configuration of the field liner on apole will still permit water drainage from the field liner ashereinafter explained.

The sheet element of this second embodiment field liner, in itsconfiguration in which it defines an elongate sleeve, also may beprovided on a roll including a plurality of such sheet elements, beingseparable from the roll by severing along a defined line of weakness,which may again be a line of perforations.

For both the above embodiment field liners, the first layer of the sheetelement may be formed of polypropylene film, or any other like suitablesynthetic plastics material. The dry film biocide contained in the firstlayer of the sheet element may be of a type that provides for theprotection of the sheet element against preservative-resistantmicroorganisms.

The material forming the first layer of the sheet element also maycontain an insecticide compound therein that can protect the sleeveagainst termite attack, a typical insecticide compound being thepyrethroid insecticide, Deltamethrin.

Also for both the above embodiments of field liners, in accordance withthe invention, the second layer of the sheet element may be formed ofone of low density polyethylene and high density polyethylene. Thesecond layer of material particularly is formed of high densitypolyethylene that permits crimping of a segment of the sheet elementthat, in use, extends beyond the butt end of a pole around which thesheet element is wrapped. The second layer of the sheet element also maycontain an insecticide compound which again may be the pyrethroidinsecticide, Deltamethrin.

A field liner that includes a sheet element of materials as hereinabovedefined is particularly suitable for use on poles containing a waterborne wood preservative, such as copper-chrome-arsenate, and the like.

The sheet element of both embodiment field liners, in accordance withthe invention, also may include a third layer formed of a flexiblealuminium film that is vapour impermeable and that is laminated betweenthe said first layer and the said second layer of the sheet element. Thesaid third layer renders the sleeve resistant to fume penetration and,as such, the field liner is rendered particularly suitable for use onpoles containing oil borne wood preservatives such as creosote,pentachlorophenol, and the like. For such a field liner, the aluminiumfilm provides the sheet element with crimping qualities as hereinaboveenvisaged.

Further according to the invention, the adhesive substance applied toboth embodiment field liners as above defined may comprise an adhesivesealant and may be covered by a peel-off strip that can form a part ofthe field liner and that can be peeled-off prior to or duringapplication of the field liner onto a pole.

The effective operative length of the sheet element of both embodimentfield liners as above defined particularly is determined by the regionof the pole to be covered thereby, being at least the region of the poleto be disposed subsoil, in the operative configuration of the pole. Thelength of the sheet element also may be such that the sheet element, inthe operative configuration thereof, when secured on a pole, can extendbeyond the butt end of the pole as hereinabove envisaged.

The invention extends also to a roll of field liners, in accordance withthe invention, in which the sheet elements of the field liners form theroll and are separable from the roll by severing thereof along definedlines of weakness, e.g. lines of perforations.

Still further, the invention extends to the combination of a pole and afield liner, in accordance with the invention, with the field linerapplied to the pole.

The mode of application of the field liner of the invention on a poleclearly is determined by the configuration of the field liner. For anembodiment field liner including merely a substantially rectangularsheet element, the sheet element is tightly wound around the pole. Forthe embodiment field liner in which the sheet element thereof forms asleeve, the sleeve is located over the pole and then wrapped around thepole. For both embodiments, the adhesive substance provides for thesecure location of the field liner following wrapping thereof around apole.

Further features of the field liner of the invention are describedhereafter, with reference to two examples of field liners that areillustrated in the accompanying diagrammatic drawings. In the drawings:

FIG. 1 illustrates in three dimensions the configuration of a firstembodiment of a field liner for protecting a timber pole against subsoildecay, in accordance with the invention, and its mode of applicationonto a timber pole;

FIG. 2 shows in side view a first possible configuration of a portion ofa sheet element for forming a field liner, in accordance with theinvention;

FIG. 3 shows in side view a second possible configuration of a portionof a sheet element for forming a field liner, in accordance with theinvention; and

FIG. 4 illustrates in three-dimensions the configuration of a secondembodiment of a field liner for protecting a timber pole against subsoildecay, in accordance with the invention, and its mode of applicationonto a timber pole.

Referring initially to FIGS. 1 to 3 of the drawings, a first embodimentof a field liner for protecting a timber pole against subsoil decay, inaccordance with the invention, is designated generally by the referencenumeral 10. The field liner 10 comprises a sheet element 11 that definesa substantially rectangular configuration and that is separable from aroll 13 including a plurality of such field liners. Particularly, afield liner 10 is separable from the roll 13 by severing the field linerfrom the roll 13 along a line defined by perforations 12.

The sheet element 11 has a strip 14 of an adhesive sealant appliedthereto along the operative length thereof, adjacent the operativelongitudinal edge 16 thereof, the adhesive sealant having a peel-offstrip 17 applied thereto, for covering the strip 14 while the sheetelement 11 forms a part of the roll 13.

The sheet element 11 forming the field liner 10 is in the form of alaminate structure, one particular configuration of this sheet element,as shown in FIG. 2, including a first layer 18, that is formed of aflexible, liquid impermeable, non-biodegradable synthetic plastics filmmaterial such as of polypropylene film, a second layer 20, that isformed of a flexible, liquid impermeable, non-biodegradable syntheticplastics film material that is tear resistant, such as low densitypolyethylene film, and a third layer 22, of a flexible aluminium filmthat is vapour impermeable and that is laminated between the first layer18 and the second layer 20.

An alternative configuration of the sheet element 11 is illustrated inFIG. 3 of the drawings and includes only a first layer 24 and a secondlayer 26 that are the equivalent of the layers 18 and 20 respectivelyand that are laminated directly onto one another. The material formingthe layers 18 and 24, respectively, of the two configurations of thesheet element 11 contain a dry film biocide therein and, optionally,also an insecticide compound such as the pyrethroid insecticide,Deltamethrin. The materials forming the respective layers, 20 and 26, ofthe two configurations of the sheet element 11 also may have aninsecticide compound contained therein which, again, may be thepyrethroid insecticide, Deltamethrin.

In order to apply the field liner 10 to a timber pole 30, a sheetelement 11 forming the field liner 10 is first separated from a roll 13(see FIG. 1B), whereafter it is placed on a substantially planar worksurface, where the timber pole is placed on the sheet element 11 (seeFIGS. 1C and 1D). The peel-off strip 17 is then removed from theadhesive strip 14 (see FIG. 1E), whereafter the sheet element 11 iswound onto the timber pole 30, until fully wound thereon (see FIGS. 1Eand 1F). Thereafter, the adhesive sealant serves to secure the sheetelement 11 on the pole 30.

The effective length of the sheet element 11 forming the field liner 10particularly is such that it covers the entire region of the pole 30that will be disposed subsoil, in use, while extending also beyond thebutt 32 of the pole, as is clearly illustrated. The segment of the sheetelement 11 extending beyond the butt of the pole can then be crimped tocover partially this butt of the pole (see FIG. 1G), this crimping beingfacilitated by the aluminium film 22, if the sheet element 11 is formedof layers as shown in FIG. 2. If the sheet element 11 is of theconfiguration as shown in FIG. 3, the layer 26 can be formed of highdensity polyethylene film, particularly such a film that will permitcrimping also.

A field liner formed of a sheet element as shown in FIG. 2 isparticularly suitable for use on poles containing an oil borne woodpreservative such as creosote, pentachlorophenol, or the like, thealuminium film being vapour impermeable and thus resisting fumepenetration. A field liner formed of a sheet element as shown in FIG. 3is particularly suitable for use on poles containing a water borne woodpreservative, such as copper-chrome-arsenate, or the like, in respect ofwhich fume penetration is not a factor and an aluminium film is thus notrequired.

Crimping of the field liner over the butt of a pole particularly servesto at least reduce leaching of preservative from the pole when disposedin its operative upright configuration in a body of soil, the remainingaperture 40, that is still defined, permitting water drainage and henceensuring that the butt of the pole cannot become anaerobic and thus beexposed to subsoil decay by anaerobic bacteria.

Referring now to FIG. 4 of the drawings, a second embodiment of a fieldliner for protecting a timber pole against subsoil decay, in accordancewith the invention, is designated generally by the numeral 50. The fieldliner 50 is formed of a sheet element 52 that is configured to form anelongate sleeve (see FIG. 4C), the sleeve, when disposed in a flatconfiguration as shown in FIGS. 4A and 4B, having a strip 54 of anadhesive sealant applied thereto along a longitudinal edge thereof. Thestrip 54 is covered by a peel-off strip 55 which can be removed from thefield liner prior to the application thereof onto a pole (see FIG. 4B).One end 56 of the field liner 50 is partially sealed, the field liner 50thus forming an effective pocket that has a hole 58 therein, as is shownclearly in FIG. 4C.

The sheet element 52 forming the sleeve again is in the form of alaminate structure, particularly a structure equivalent to the structureof the sheet element 11 of the field liner 10 as above described, withreference to FIGS. 2 and 3 of the drawings.

It is envisaged that the field liner 50 can be provided as a separateunit or, alternatively, in a roll form from which individual fieldliners are separable. The effective length of the sleeve is such thatthe field liner 50 can cover the area of a pole to be protected by beinglocated over the pole, the partially sealed end 56 of the sleevefacilitating the required location of the field liner 50 on a pole.

It will be appreciated that the effective diameter of the sleeve issubstantially larger than that of a pole on which the body is to belocated, this being apparent from FIGS. 4C and 4D. For the applicationof the field liner 50 on a pole 60, the pole 60 is inserted into thesleeve until the butt of the pole bears against the partially sealed endof the sleeve. The sleeve is then wrapped tightly around the pole,whereafter the strip 54 of the adhesive sealant can serve to secure thefield liner on the pole. Crimping of the excess material providedadjacent the butt of the pole can again be effected in order to coverthis butt of the pole in a configuration in which leaching ofpreservative from the pole, while the pole is disposed in an operativeupright configuration in a soil body, is effectively reduced. An opening64 again remains in order to permit required water drainage and,thereby, prevent subsoil decay of the pole by anaerobic bacteria ashereinabove envisaged.

It must be appreciated that the specific configurations of bothembodiments of the field liner of the invention as above described aregreatly variable, whilst still incorporating the essential features ofthe two field liners which facilitate the convenient application thereofonto timber poles. Also, the material types forming the layers of thesheet element of which the field liners are formed are greatly variableand particularly will be determined by particular applications of fieldliners and particular conditions to which poles having field linersfitted thereon may be exposed, in use.

The field liners as described render application onto polessignificantly easier and quicker than when compared with the applicationof known field liners onto poles, thus facilitating the use of fieldliners and the provision of field liners, e.g. in a roll form, or thelike.

1. A field liner for protecting a timber pole against subsoil decay,which includes a sheet element in the form of a laminate structureincluding a first layer of a flexible, liquid impermeable,non-biodegradable synthetic plastics film material that contains a dryfilm biocide therein and a second layer of a flexible, liquidimpermeable, non-biodegradable synthetic plastics film material that istear resistant, the sheet element being configured to permit wrappingthereof around a pole for covering the region of the pole to beprotected and having an adhesive substance applied thereto in a regionthereof that permits securing of the location of the sheet element on apole when wrapped around the pole with its first layer abutting the poleby adhering the said region of the sheet element to an opposing regionof the sheet element when wrapped around the pole.
 2. A field liner asclaimed in claim 1, in which the sheet element is configured to define arectangular configuration, that permits wrapping thereof around a poleby winding it on the pole, and the adhesive substance is applied theretoas an adhesive strip along an operative longitudinal edge regionthereof.
 3. A field liner as claimed in claim 2, in which the sheetelement is provided on a roll including a plurality of sheet elements,being separable from the roll by severing along a defined line ofweakness.
 4. A field liner as claimed in claim 1, in which the sheetelement is configured to define an elongate sleeve that has the firstlayer of material forming the operative inside thereof and the secondlayer of material forming the operative outside thereof and that permitsloose location on a pole for covering the region of the pole to beprotected and hence wrapping around the pole into a tight configurationof the sheet element on the pole, the second layer of material having anadhesive substance applied externally thereon in a region thereof thatpermits securing of the location of the sheet element in its said tightconfiguration on a pole when wrapped around the pole by adhering thesaid region to an opposing region of the sheet element when wrappedaround the pole in the said tight configuration thereof.
 5. A fieldliner as claimed in claim 4, in which one end of the sleeve defined bythe sheet element is at least partially sealed to form a pocket, the atleast partially sealed end of the sleeve, in use, serving to determinethe location of the sleeve on a pole by preventing the butt end of thepole to extend beyond the said at least partially sealed end of thesleeve.
 6. A field liner as claimed in claim 4, in which the sheetelement, in its configuration in which it defines an elongate sleeve, isprovided on a roll including a plurality of such sheet elements, beingseparable from the roll by severing along a defined line of weakness. 7.A field liner as claimed in claim 1, in which the first layer of thesheet element is formed of polypropylene film.
 8. A field liner asclaimed in claim 1, in which the dry film biocide contained in the firstlayer of the sheet element is of a type that provides for the protectionof the sheet element against preservative-resistant micro organisms. 9.A field liner as claimed in claim 1, in which the first layer of thesheet element contains an insecticide compound therein.
 10. A fieldliner as claimed in claim 9, in which the insecticide compound is thepyrethroid insecticide, Deltamethrin.
 11. A field liner as claimed inclaim 1, in which the second layer of the sheet element is formed of oneof low density polyethylene and high density polyethylene.
 12. A fieldliner as claimed in claim 11, in which the second layer of material isformed of high density polyethylene that permits crimping of a segmentof the sheet element that, in use, extends beyond the butt end of a polearound which the sheet element is wrapped.
 13. A field liner as claimedin claim 1, in which the second layer of the sheet element contains aninsecticide compound.
 14. A field liner as claimed in claim 13, in whichthe insecticide compound is the pyrethroid insecticide, Deltamethrin.15. A field liner as claimed in claim 1, which includes a third layerformed of a flexible aluminium film that is vapour impermeable and thatis laminated between the said first layer and the said second layer ofthe sheet element.
 16. A field liner as claimed in claim 1, in which theadhesive substance comprises an adhesive sealant.
 17. A field liner asclaimed in claim 1, in which the adhesive substance is covered by apeel-off strip that can form a part of the field liner and that can bepeeled-off prior to or during application of the field liner onto apole.
 18. A roll of field liners, as claimed in claim 1, in which thesheet elements of the field liners form the roll and are separable fromthe roll by severing thereof along defined lines of weakness.
 19. Incombination, a pole and a field liner as claimed in claim 1, with thefield liner applied to the pole.
 20. (canceled)